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Automotive

April 28, 2009

When I was a young boy, I became a big fan (and still am) of Syd Mead and his vision of the 21st century as viewed from the 1960s. I remember my mom buying me a book for my birthday on the history of the automobile. Not only did it include the invention and history, but wonderful depictions of future automobiles that were hydrogen powered and could jack up their wheels and take flight like an aircraft using lift jets - obviously Syd’s work. There were visions of computerized highways in the sky where your flying car would simply join others in route and travel at speeds over 300 MPH.

Looking back, it’s very sad to me that the wonderful artwork of Mr. Mead was never realized... however, that didn’t stop some people from trying. There have been many references to the Moller flying car which uses multiple propeller engines to lift the entire vehicle and push it through the air at high speeds. Moller’s vision was the same as Mead’s - a computerized highway in the sky taking control of the vehicle and getting you to your final destination in the most efficient way.

So what happened to that wonderful future of flying vehicles? The most likely problem was a little thing called gravity and the power needed to overcome it. Another is the need (or lack thereof) to remove traffic from its terrestrial bounds. However, many other innovations have been made in the automotive sector. A few of these advances include computerized engine controls, electronic fuel injection, air bags (a personal favorite of mine), GPS navigation, computerized vehicle management, back-up sonar and cameras plus many more. A great deal of these would be considered science fiction in the 1960s, but are realities today.

With the pressures of our new energy crisis temporarily clipping our wings, attention has been focused on making the entire system more efficient. Many of you are already driving first and second generation gas-electric hybrids. There are more of those on the way. But the next big step will be fully electric cars (see my previous blogs on electric cars). Technology to quickly charge electric vehicles is coming and solutions to extend battery life or replace batteries altogether are on the horizon.

Still, there are a great number of improvements that can be made to our current production lineup hitting the roads as well as the roads themselves. Efficiency improvements are not restricted to a single function. Large gains are often found by re-architecting the way something operates. That is, simply improving the efficiency of a car’s engine may not be the best solution if you are stuck in traffic most of the time. One solution to traffic is turning the engine off while stopped (a problem if - like me - you live in Florida and the air conditioner runs off the engine). This is one of many improvements that help the car’s fuel efficiency, but not the infrastructure. Electronics, sensors and computerized traffic management can make roads far more efficient by routing traffic around congestion (like packets on the Internet). People are the other problem - they need to use the information provided by the highway wisely while driving. Ignoring (or not believing) information interferes with the solution.

Like many things that influence humans, there must be an incentive. For instance, buying a gas-hybrid at a premium is influenced by a high price for fuel. A solution that might work to improve road efficiency is toll roads that dynamically change the fee to influence usage. That is, at peak times (6:00 AM to 9:00 AM and 3:00 PM to 6:00 PM), rates go up sharply. At low utilization or off-peak times (e.g. 1:00 AM to 4:00 AM), tolls could be free or very inexpensive. Trucking companies may choose to move freight during these times leaving the cars to use roads during higher peak times. If your car’s navigation system knew the cost of these tolls as well as real-time traffic conditions, you could either elect to go the cheapest route or the fastest route. Giving people these choices (and showing them the total cost on the dash board including the fuel they will consume) will have a bigger influence on the efficiency of the system than simply using computerized road-side signs to inform of impending traffic.

This is not unlike what the power companies are proposing to control loading on their power plants and networks. Smart Grid technology would update meters during peak times to increase the price of a kilowatt-hour. The consumer’s home systems could monitor the metered rate and adjust usage accordingly. For instance, a washing machine could "pause" a cycle while waiting for the rates to go down (so you soak your cloths a bit longer...). This prevents brown-outs or other more serious side effects while keeping loads on the plants constant improving overall efficiency. See my prior blog, "Will Energy Costs Revive Home Automation".

Until we figure out the relationship between gravity and the forces we can control, we’ll probably be stuck to our terrestrial roots. But not to worry... I guess I’m somewhat comfortable with the thought that running out of fuel (or stored energy) will not cause me to plunge to my death. I’m somewhat attached to the thought of simply "pulling over" to the side of the road - for now anyway. Till next time...

August 11, 2008

Today the surge in fuel prices has started a trend in improving mileage and adopting alternative fuels as well as driving consumers to gas-electric hybrids and soon fully electric vehicles. What’s more interesting about this trend is the current hidden benefits associated with the movement to electricity as an energy source for transportation. Let’s take a look at an example of a hidden benefit that early adopters of electric vehicles will enjoy - but probably not forever...

First, let’s take a look at taxation on motor vehicles. The gasoline tax began in 1932 when Congress placed an excise tax on the fuel, but it wasn’t until 1956 that all of the funds collected went to highway spending through the Federal-Aid Highway Act. Additional taxes have been added by local and state governments totaling about 11% to the price of the fuel. So roughly US$0.44 of the purchase price of a gallon of gasoline (US$4.00) is taxes. These moneys are used for road improvements, maintenance, public transportation projects, etc.

So, if vehicle A gets 15 MPG and vehicle B gets 50 MPG, which owner is paying more tax to build roads and maintain the ones we have? I’m sure you’ve guessed... the owner of the lower mileage vehicle. That gas guzzler you’re driving is costing you more in tax than if you drove a compact car. If both vehicles are driven 15,000 miles per year, then the owner of vehicle A will pay US$440 in taxes and the owner of vehicle B will only pay US$132 which is less than one third as much.

OK, so you might say, "big deal- the less efficient car is probably larger and does more damage to the road so they should pay more". I might buy that, but here’s another scenario. What if vehicle A gets 30 MPG and the vehicle B is a plug-in hybrid that gets 200 MPG. Both vehicles weigh the same and are about the same size - now which owner gets a tax break? Obviously, the gas-electric hybrid owner does. They will only pay US$33 versus the owner of the gas powered vehicle who will pay US$220.

Now what happens when your vehicle doesn’t use gasoline at all? A fully electric car that is plugged into your home outlet every night is not (currently) taxed at all. You would drive on non-toll roads effectively for free - no tax. Now the question is, should the government leave it that way for the near future to help convert people to gas-electric hybrids and fully electric cars? In an earlier post I talked about the future of fully electric automobiles (see: A Case Study of Electric Vehicles). In that study, I also noted that the cost of ownership is far less for electric cars than for gasoline powered vehicles. Once a practical electric vehicle (i.e. reasonable cost, 400+ miles to the charge, good size, no battery replacement, etc.) reaches the market, more people will begin to migrate.

In an electric vehicle economy, the question then becomes who carries the burden of road maintenance and construction? Could you tax the electricity used to charge the car? The power company simply adds an additional "vehicle" tax to your power bill... but what portion of your electric bill is for charging your car? What if you live in an apartment and drive 90 miles each day to work and your friend lives in a 5000 square foot home and drives 3 miles to work? I would guess that taxing electricity directly would not be very equitable. And what if your house was powered by solar power or the car itself had solar panels in the roof that charged it up any time it’s in sunlight? Now, how do you tax it? You could add an "ad valorem" tax (i.e. a tax based on the car’s value) to the license tag. Now electric vehicles costing more than a conventional car would pay more. This still does not address the usage tax which gasoline taxes provide.

In an electric vehicle future there is the possibility that the license tag itself will keep track of mileage for you. Once a day it will report your mileage on public roads as you drive by readers in the road-way and you’ll get a tax bill either at the end of the month or once a year (similar to a property tax bill). This would fairly tax each vehicle based on usage and allow any source of energy to charge it. It would also provide an incentive to drive less - possibly telecommute more and in the process save energy. Today, modern toll roads use electronic passes to collect tolls - this method could simply be an extension of the current technology. Maybe fully electric vehicles will have this function built in when you buy it...

So, for now get your electric or gas-electric hybrid and cash in on your tax break while it lasts... there will be interesting times ahead for sure! Let me know what you think? Till next time...

June 23, 2008

Over at National Semiconductor, we've been working on metrics for measuring and improving the performance to power ratios of our devices. During some recent meetings I was talking to a colleague about electric vehicles. The question came up, "if your car doesn't have a fuel tank, how do you measure the MPG (KPL) of the vehicle?" Does the efficiency of the charger affect your mileage? Does the battery replacement cost get included into the cost of the fuel or the cost of ownership? Here's my take on this - and it makes me think I want a fully electric car - but maybe not yet...

So you are the proud owner of a new "Zolt" (a fictitious car company) "Wunderwatt" (a fictitious automobile) fully electric 4-door sedan. It came complete with regenerative braking. You found this "feature" is a bit strange - when you take your foot off the accelerator pedal, the car immediately starts to slow down - much sooner than a conventional car. This is due to the motor now running as a generator to charge the battery. This feature really improves the "time between charges" - a measure of how efficient the automobile is with the energy it stores. Here are Zolt's specifications for the Wunderwatt:

Battery Capacity: 75 kW-hr (Lithium Ion)Mileage on a single charge: 400 miles (643 kilometers) - based on non-stopTime to recharge: 9 hours (110VAC), 4.5 hours (220VAC)Battery Life: approximately 4 years (degrading from age due to temperature)Battery Replacement Cost: approximately $5000 US (hopefully less)

To figure out how the charge relates to mileage, we must first calculate the equivalent of the MPG rating - in this case Miles (or Kilometers) per kW-hr of stored energy. This will be an average based on the car manufacturer's rated distance on a charge, but might actually be lower (or higher due to regenerative braking). The mileage on a single charge could be calculated by running the motor on a dynamometer at some fixed speed until the battery goes dead. This is not a real world method, so there needs to be some standard for measuring this value. To calculate the MPkW-hr you simply divide the total mileage on a single charge by the battery capacity. In the case of the Wunderwatt, it is 400 / 75 = 5.34 MPkW-hr or 644 / 75 = 8.59 KPkW-hr. So for each kilowatt-hour of storage you can drive approximately 5.34 miles (8.59 kilometers).

Next, we need to estimate the annual usage of the vehicle. Most families will average about 15000 miles (24140 kilometers) per year. This may vary, but it's a number used by many automobile leasing companies for annual usage, so it's probably pretty accurate. To calculate annual power consumption we simply divide this number by the MPkW-hr (KPkW-hr) number which yields kilowatt-hours consumed by the vehicle. In our case we get 15000 / 5.34 = 2810 kilowatt-hours which are also the same for metric. The average US household uses roughly 900 kilowatt-hours per month - so the car uses roughly the same power over a year that an average US household does in 3 months, but there are several other factors we need to consider.

The car does not have a 400 mile long extension cord, it has batteries. Batteries are not 100% efficient at charging or discharging, so we need to introduce a battery efficiency loss factor - for Lithium Ion, we'll use 0.998 which is negligible and we'll ignore it. Additionally, the charger is converting line power to charge current. This process can be anywhere from 70% to 90% efficient (and possibly higher), so let's split the difference at 80% and introduce a charge efficiency loss factor of 0.8. We now divide the total power used by the vehicle by our loss factor: 2810 / 0.8 = 3513 kilowatt-hours of input energy into the car.

Now that we have an energy consumption number, the annual "fuel" cost can be calculated. We simply take the energy consumed and multiply by the cost per unit energy. For an electricity cost of $0.15 US per kW-hr, we get 3513 kW-hr * 0.15 = $527 annual electricity cost. Now, your amount may be higher or lower depending on the local cost of electricity. But there is still another factor, the replacement cost of the batteries - they have a finite lifespan. The question is whether to include that in the devaluation of the vehicle, the maintenance cost, or the fuel cost.

If we include cost of replacing the batteries with the fuel cost, then we need to amortize the cost of the battery over the lifespan. Lithium Ion batteries age - the aging process has been slowed down on modern cells, but due to elevated temperatures in a vehicle (e.g. sitting in a hot parking lot every day), it may only last 2-3 years. For our Wunderwatt model, the lifespan is specified at 4 years with a replacement cost of $5000 US. That amortizes out to $1250 per year. So the total cost of fuel for the vehicle is roughly $1777 annually.

To compare that with an average gasoline powered sedan that gets 25 MPG (10.6 KPL) we'll need to calculate the fuel cost. Using an average cost per gallon of regular (87 octane) gasoline of $4.00 US (as of June 15th, 2008), the cost of driving the same 15000 miles would be (15000 / 25) * 4.00 = $2400 per year. This was quite a surprise to me! Even including the battery replacement cost on an annual basis, driving this mythical electric car is still cheaper than a conventional gasoline powered vehicle. The overall costs should also be cheaper since there are really no oil changes, fewer moving parts in the electric car and regenerative braking (which was not considered in the mileage of the electric car).

But would I buy this car if it came out tomorrow - the answer is maybe... My perfect electric car would have the performance of a gasoline powered sedan, but use a battery system that does not degrade with time and outlasts the vehicle. There is on-going research in the area of double-layer carbon nanotube supercapacitors. See this article from Science Daily:http://www.sciencedaily.com/releases/2005/02/050217224708.htm

The ability to densely pack carbon nanotubes inside these capacitors provides much more surface area to store charge. They effectively will never wear out and have endless charge-discharge cycles. Initially these capacitors may find their way into the regenerative braking system to reabsorb as much of the vehicle's kinetic energy and use that for acceleration reducing the size and weight of the on-board batteries.

The complete equation is shown below in case you want to enter your own values. If you can think of any additional terms or you have an improved equation, drop me an email or comment here on the blog. Till next time...

Equation 1 - Electric Vehicle Cost of Ownership

Where:- CoO is Annual Cost of Ownership- Sc is Distance traveled on a charge- Sa is Distance traveled annually (varies by user)- Ec is the energy capacity of the battery (usually in kW-hr)- eff is the charger conversion efficiency- Ce is the cost of energy (usually in $/kW-hr)